1. Field of the Invention
The present invention relates to a lens frame drive apparatus for an image pickup apparatus that individually drives a plurality of lens frames holding a plurality of lens groups, respectively, inside a photographing optical system in an image pickup apparatus.
2. Description of Related Art
In a lens frame drive apparatus for a conventional image pickup apparatus, when, e.g., a zooming or focusing operation is performed, it is necessary to move a plurality of lens groups in an optical axis direction, respectively, by different amounts of movement. Therefore, in addition to, for example, drive mechanisms with drive sources dedicated to zooming and focusing, respectively, various drive mechanisms in which two types of cams/threads are formed at one drive shaft and such drive shaft is driven to rotate by one drive source, thereby providing an operation similar to the above, have been proposed in, for example, Japanese Examined Utility Model Registration No. 2521866 and Japanese Patent Application Laid-Open Publication No. 4-317015 and put into practical use.
The lens frame drive apparatus for an image pickup apparatus disclosed in Japanese Utility Model Laid-Open No. 2521866 is configured so that a first feed screw and a second feed screw are integrally formed and a first group moving frame is moved by the first feed screw and a second group moving frame is moved by the second feed screw by means of a driving force of a drive source, respectively, in the optical axis direction by different amounts of movement. Furthermore, the second feed screw is configured so as to move in the optical axis direction via a cam rotated by the driving force of the drive source.
The lens frame drive apparatus for an image pickup apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 4-317015 is configured so that a drive ring for both focusing and zooming and a drive ring for zooming are joined to each other via clutch means and, during idling of the clutch means, only the drive ring for both focusing and zooming is rotated to perform focusing and during the clutch means being engaged, both the drive ring for focusing and zooming and the drive ring for zooming are rotated to perform zooming.